Fan



' Dec. 6, 1938. QN. M LAN E 2,139,416

I I FAN Filed Nov. 20, 1937 In venfor C/meLEs N. M LANE by %J% attorney iiginner portion l3 of a hub member.

Patented D... a, 1938 UNlTED srATEs PATENT [opt-mg"- 'v 2,139,410 7. I

to B. F. Boston, Mass.

Sturtevant Company, Hyde Park,

Application November 20, 1937, Serial No. 175,691

' Claims. (01. 230-114) This invention relates to centrifugal fans employing adjustable inlet vanes of the type shown by the United States Patent No. 2,063,174, to M. S. Leonard, and relates more particularly to 5 means for preventing foreign matter from-being drawn by the action ofthe fans into the vane adjusting mechanisms.

, Centrifugal fans of the induced draft type are commonly used for drawing the flue gases from steam power plants. -Where adjustable inlet vanes are used,the vane rotating mechanisms are usually mounted in the fan inlets so as to be exposed to the fluid passing through the inlets. The flue gases from steam plants contain cinders,

corrosive gases and other foreign matter which is forced under the pressure created bythe fans,

to enter the mechanism for rotating the vanes;

corroding and clogging same.

According to this invention, clear air is drawn into the vane adjusting mechanism which onposes and prevents the entrance of flue gases, and the mattercarried by same.

An object of the invention is to prevent the entry of undesirable matter into the-vane adlusting mechanism of induced draft fans.

Another and more definite object of the invention is to draw clean fluid into the vane adjusting mechanism of induced draft fans to oppose the [entry of unclean fluid. 1 3o Thein-vention will now bedescribed with reference to the drawing which shows an elevation view in section of a fan embodying this invention.

The fan illustrated has'the casing b to which" is attached the member 6 forming a converging 5 inlet passage which terminates adjacent the fan wheel 1. The wheel I is mounted on the shaft,

. 8 which is supported by the bearing pedestal 9. The member Ill encloses the inlet to the fan and forms a passage H! which communicates with the source of the fluid to be moved .by the fan.

The vanes H are rotatable to vary the spin of the air entering the fan wheel and are mounted uponthe bearings I2 which rotate around pivot rods which extend between the member 6 and the The outer portion M of the hub member is journaled to receive the rotary member 15 which has in its inher portion, a plurality of channels in which the followers .IG attached to the, pivot rod bearings 50 I2 extend. The outer portion of therotary mema ber 15 is formed as a ring gear, the teeth of which mesh with the teeth of the bevel gear ll. The

' bevel gear 11 is rotated by the shaft I 8 which extends to any suitable control point to be rotated manually or under automatic control. The

selves into the ordinary housings for the vane 10 adjusting mechanisms which are necessarily mounted in the fan inlets, through the several openings through which the pivot rods and control members, etc'., extend. The corrosive gases cause corrosion of the device and the cinders 15 collect within the device to hinder its adjustment.

This difliculty is overcome according to this invention by enclosing the mechanism within the housing 20 which in the embodiment illustrated, is an extension of the hub member; by tapping 20 the housing 20 at 2| to receive one end of the pipe 22, and by extending the other end of the pipe 22 through the casing wall 23 into a region of clear air.

.The housing 20 is in the path of the flue gases 25 which if the pipe 22 were not provided, would pass through the housing 20 through entering one or more of the several small openings in the housing and through'passing out of one or more of the other small openings. The housing 20is however under sub-atmospheric or negative pressure due to the suction of the fan. The pipe 22' extends at one end into the area of clean air under atmospheric pressure, exterior the fan casing and at the other end into the area of lower pressure at the'housing 20. The difference in pressures causes, when the fan is operating, clean air to pass through the pipe 22 into the housing 20 and from the housing 20 through the several small openings. previously referred to,

into the fan wheel. Thus, when the fan is operating, there is' a continuous flow of clean air through the pipe 22 andhousing 120 which flow opposes and prevents the flow oiflue gases into the housing.

' I While one embodiment of the invention has been described for the purpose of illustration, it

means forming an inlet passage around said shaft into said blades, a plurality of rotatable vanes in said passage, mechanism in said passage for rotating said vanes, a housing around said mechanism, means forming a passage for connecting said first mentioned passage with a source of gas to be moved, and means connecting the interior of said housing with gas from another source.

2. A fan comprising in combinatioma plurality of fan blades, a shaft for supporting said blades, means forming aninlet passage around said shaft into said blades, a plurality oi. rotatable vanes in said passage, mechanism in said passage for rotating said vanes, a housing around said mechanism, means forming a relatively large passage for connecting said first mentioned passage with a source of gas to be moved, and means forming a relatively'small passage connecting the interior of said housing with gas Irom'another source.

3. A fan comprising in combination, a plurality of fan blades, a shaft for supporting said blades,

means forming an inlet passage around said shaft into said blades, a plurality of rotatable vanes in said passage, mechanism in said passage for rotating said vanes, a housing around said mechanism, means comprising walls forming a relatively largepassage for connecting said first mentioned passage with a source-oi gas to be moved, and means forming a relatively small passage extending through one oi. said walls and connecting the interior of said housing with gas from another source.

4. A fan comprising in combination, a plurality of fan blades, a shaft for supporting said blades, means forming an inlet passage around said shaft into said blades, a plurality of rotatable vanes in said passage, mechanism in said passage for rotating said vane, ahousing around said mechanism, means comprising walls forming a relatively large passage for connecting said first mentioned passage with a source of gas to be moved, and a pipe extending through one of said walls and connecting the interior of said housing with gas from another source.

' 5. A fan comprising in combination, a plurality of Ian blades, a'shaft for supporting said blades,

v means forming an inlet passage around said shaft 'into said blades, a plurality of rotatable vanes in said passage, mechanism in said passage for rotating said vanes, a housing around said mechanism, means forming a passage for connecting said first mentioned passage witha source of fluid to be moved, and means'for moving air through said housing in a direction opposing the entry of said fluid into same.

CHARLES N, McLANE. 

